Optic nerve hypoplasia (ONH), congenital underdevelopment of one or both optic nerves, was once thought to be rare but is now recognized as a major etiology of subnormal vision in children and is a leading cause of congenital blindness at CHLA. This study is designed to provide preliminary data about the factors that may be involved in the formation of ONH prior to birth. It is also designed to correlate those factors with the severity of the disease and its associated medical conditions.